diff --git a/CHANGELOG.md b/CHANGELOG.md
index 90e368da8bf..48903ead425 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 ### Fixed
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)
 * CompensatingWriteErrorInfo reported string primary keys as boolean values instead ([PR #5938](https://github.com/realm/realm-core/pull/5938), since the introduction of CompensatingWriteErrorInfo in 12.1.0).
+* Fix a use-after-free if the last external reference to an encrypted Realm was closed between when a client reset error was received and when the download of the new Realm began. ([PR #5949](https://github.com/realm/realm-core/pull/5949), since 12.4.0).
 
 ### Breaking changes
 * Rename RealmConfig::automatic_handle_backlicks_in_migrations to RealmConfig::automatically_handle_backlinks_in_migrations ([PR #5897](https://github.com/realm/realm-core/pull/5897)).
diff --git a/src/realm/object-store/sync/sync_session.cpp b/src/realm/object-store/sync/sync_session.cpp
index 4c295cc525d..7f47d15f009 100644
--- a/src/realm/object-store/sync/sync_session.cpp
+++ b/src/realm/object-store/sync/sync_session.cpp
@@ -335,10 +335,18 @@ void SyncSession::download_fresh_realm(sync::ProtocolErrorInfo::Action server_re
                 server_requests_action);
         }
     }
+
+    std::vector<char> encryption_key;
+    {
+        util::CheckedLockGuard lock(m_config_mutex);
+        encryption_key = m_config.encryption_key;
+    }
+
     DBOptions options;
-    options.encryption_key = m_db->get_encryption_key();
     options.allow_file_format_upgrade = false;
     options.enable_async_writes = false;
+    if (!encryption_key.empty())
+        options.encryption_key = encryption_key.data();
 
     std::shared_ptr<DB> db;
     auto fresh_path = ClientResetOperation::get_fresh_path_for(m_db->get_path());